Generally, cinema front projection screens are manufactured using low modulus substrates such as plasticized polyvinyl chloride (PVC), approximately on the order of 300 microns in thickness. One of the benefits of such a substrate is that distortions that affect the local surface normal, which can affect screen appearance, are removed when the material is placed under tensile load. This is particularly so for screens with highly sloped gain profiles, such as those used to preserve polarization in stereoscopic 3D systems.
Conventional screens are manufactured according to a “coat-after-converting” process. That is, roll stock is converted to full-size by joining vertical strips, one meter or more in width, after which and when appropriate an optically functional coating is applied. In a cinema environment, sound systems are often mounted behind the screen, requiring periodic perforations for high frequency transmission. The joining of the vertical strips may take into account registration of perforations across the seam, in order to avoid spatial-averaged intensity non-uniformities that can be visually observable. Moreover, the joining process attempts to avoid gaps, wrinkles, distortions, and anything that affects the screen surface in a manner that is visually resolvable. There are a few accepted joining methods for PVC screens, each with process-specific challenges.